1. Field of the Invention
The present invention relates to a display device, and more particularly to a display device which is capable of changing a view angle range.
2. Description of the Related Art
With the development of display technology in recent years, display devices that can be viewed in a wide angle range have been put to practical use. Portable information terminals incorporating display devices such as liquid crystal displays have also been in widespread use. If the information displayed on a portable information terminal is to be viewed by a plurality of people, then it is desirable that the information be visible in a wide angle. On the other hand, there is a situation where the displayed information should not be viewed by other people. Consequently, there is a demand for display devices capable of switching between a wide view angle range and a narrow view angle range for viewing the information displayed on the display screen depending on the way in which the display device is used.
One example of display device which can meet the above demand is disclosed in JP06-105305A. The disclosed display device will be described below with reference to FIG. 1 of the accompanying drawings. FIG. 1 is a view of the display device disclosed in the above publication, the display device being relevant to the present invention.
As shown in FIG. 1, the display device has liquid crystal display 101 with lenticular lens plate 102 mounted thereon. On the average, each lens of lenticular lens plate 102 is associated with two pixels. In particular, pixel 103 is disposed at the center of each lens, and pixel 104 is disposed at an end thereof.
For the display device to display an image in a narrow view range, the display device supplies only pixels 103 with a display signal. At this time, the displayed image can be viewed only in view range 105. For the display device to display an image in a wide view range, the display device simultaneously supplies pixels 103, 104 with a display signal. At this time, the displayed image can be viewed not only in view range 105, but also in view ranges 106, 107.
As described above, the display device disclosed in JP-A No. 6-105305 allows different view ranges to be selected by controlling the supply of display signals to pixels 103, 104.
However, the disclosed display device suffers the following difficulties:
Firstly, the size of view range 105 is determined by the size of pixel 103. Therefore, if the view range is to be set to a narrow range, then the size of pixel 103 needs to be reduced, and the display device displays images with a low luminance level, i.e., dark images.
Secondly, there is a non-display area created between view range 105 and view range 106 or 107 because the gap between pixels 103, 104 is magnified by the lens. As a result, the viewer sees dark lines in the displayed image, and feels awkward about the displayed image. The darks lines are caused when both pixels 103, 104 are displayed in order to display an image in a wide view angle. As the viewer has to attempt to view the image while avoiding the dark lines, the display device, in practice, fails to provide wide view angles.